The present invention relates generally to bulb shields for use in automotive headlamp assemblies, and relates more specifically to a bulb shield which includes a part which is formed of a glass and polymer blend and is coated with a metal, such as a vacuum aluminized metal coating.
The present invention also relates generally to methods of making bulb shields which are employed in automotive headlamp assemblies, and relates more specifically to a method of making a bulb shield where the method includes a step of injection molding a part using a glass and polymer blend and then coating at least a portion of the part with metal, such as in a vacuum aluminizing process.
Automotive headlamp assemblies generally include a headlamp bulb which is positioned in a reflector. A bulb shield is mounted to the reflector, and is positioned generally in front of the headlamp bulb. While the reflector functions to reflect the light from the headlamp bulb forward, thus forming a headlamp beam, the bulb shield functions to prevent an oncoming driver from seeing a xe2x80x9chot spotxe2x80x9d in the headlamp beam.
Bulb shields typically include a cup portion which is disposed generally in front of the headlamp bulb, and portion which extends from the cup portion and mounts to the reflector or some other proximate structure. The cup portion of the bulb shield is usually relatively sharply concave, thereby providing that the light which enters the cup portion is reflected generally back to the headlamp beam.
Fabricating a bulb shield out of metal, such as out of a thin gauge steel, is difficult because of the peripheral edge of the cup portion having to meet precision requirements. Because the deep draw of the cup portion stretches the material somewhat randomly, trimming the peripheral edge of the cup portion is costly. Fabricating a bulb shield out of metal effectively provides that complex cup shapes are not possible, or at least are not economically feasible.
Instead of metal, it would be beneficial to provide a bulb shield which is at least partly formed of plastic. Plastic is not only lightweight and relatively inexpensive, but would provide that a bulb shield can be made within a plastic injection molding process, and that complex cup shapes can be formed. However, the cup portion of a bulb shield typically experiences extremely high temperatures, and most plastics which have a reasonable cost cannot endure such high temperatures. Specifically, the cup portion of a bulb shield often experiences temperatures as high as, or even higher than, 500xc2x0 Fahrenheit (260xc2x0 Celsius). Because low cost plastics cannot generally withstand such high temperatures, it has not been possible to provide a low cost, plastic bulb shield for use in an automotive headlamp assembly.
Accordingly, it is an object of an embodiment of the present invention to provide a low cost bulb shield for use in an automotive headlamp assembly.
Another object of an embodiment of the present invention is to provide a bulb shield which has a relatively complex cup shape.
Still another object of an embodiment of the present invention is to provide a method of making a bulb shield for use in an automotive headlamp assembly, where the method includes injection molding a part and coating at least a portion of the part with metal.
Briefly, and in accordance with one or more of the foregoing objects, an embodiment of the present invention provides a bulb shield for use in an automotive headlamp assembly, and a method for making same. The bulb shield includes a cup portion and a portion which extends from the cup portion and is configured for mounting to a reflector of the automotive headlamp assembly or to another, proximate structure. When the bulb shield is mounted, the cup portion is preferably generally horizontally aligned with a headlamp bulb in the automotive headlamp assembly, thereby eliminating a xe2x80x9chot spotxe2x80x9d which would otherwise be viewable when looking into the headlamp beam.
Preferably, the bulb shield includes a part made of a glass and polymer blend, and at least a portion of the part, such as a cup portion of the part, includes a vacuum aluminized coating. Such a bulb shield is relatively inexpensive and easy to make, yet can withstand the high temperatures which are typically experienced in an automotive headlamp assembly. Additionally, such a bulb shield may include a relatively complex cup shape.
Another embodiment of the present invention provides a method of making a bulb shield wherein the method includes injection molding a part made of a glass and polymer blend, and coating at least a portion of the part using a vacuum aluminizing process.